Propeller



Dec. 1924- 1,519,102

A. ASSALA PROPELLER Filed April 13, 1923 Patented Dec. 16, 1924.

UNITED STATES ANTHONY ASSALA, F DES MOINES, IOWA.

PROPELLER.

Application filed April 13, 1928.

1 0 all whom it may concern:

Be it known that I, ANTHONY AssALA, a subject of the King of Italy, residing at Des li'loines, in the county of Polk, State of Iowa, have invented a certain new and useful Propeller, of which the following is a specification.

The object of my invention is to provide a propeller of simple, durable and inexpensive construction, especially designed for use with aeroplanes.

More specifically it is my object to pro vide a propeller of this character having increased efiiciency, and in this connection it is my object to provide means for delay ing or retarding the movement of the air in a direction from the center of the propeller to the periphery thereof, so that the pro peller blades will contact with relatively still air.

A further object is to provide means for accelerating the passage of air through the central portion of the propeller, to thereby counteract the tendency for the air to move outwardly on a line from the center of the propeller toward the outer end of the blades.

My invention consists in the construction, arrangen'ient and combination of the various parts of the device, whereby the objects contemplated are attained, as hereinafter more fully set forth, pointed out in my claims, and illustrated in the accompanying drawings, in which:

Figure 1 shows a front elevation of a propeller embodying my invention.

Figure 2 shows a sectional view of same on the line 2-2 of Figure 1.

Figure 3 shows an enlarged, detail, per spective View of a portion of the tubular hub and one of the blades at the forward end thereof; and

Figure 4L shows a similar view illustrating one of the plates at the rear of the tubular hub.

Referring to the accompanying drawings, I have used the reference numeral to indicate a tubular metal hub of relatively large diameter. Formed on or fixed to the outer surface of this hub are the blade reinforcing members 11 and 12, and between them is mounted the wooden propeller blades 13, and on the outer edges of the propeller blades there is preferably a metallic binding 14.

Near the advance end of the tubular hub Serial No. 631,804.

10 there is a circular plate 15 having a circular opening at 16 to receive a propeller shaft, and near the rear end of the tubular hub 10 is another circular plate 17 through which the propeller shaft is inserted.

These plates 15 and 17 are connected with and supported by the tubular hub by means of a series of radial-blades. The ones connected to the plate 15 comprise a metal body portion 18 secured by welding or otherwise to the plate 15 at its inner end and connected to an angular flange 19 at its outer end.

.The flange 19 is permanently connected by welding or otherwise to the interior of the tubular hub.

The forward or advance edge of the blade 18 is preferably rounded at 20, as clearly shown in Figure 3, and the rear end 21 is preferably straight. The pitch of the blade 18 is made slightly greater than the pitch of the propeller blac e 13, for purposes hereinafter made clear.

The plate 17 is connected to the hub by means of a series of blades, each comprising a body portion 22 firmly connected by welding or the like with the plate 17 at its inner end, and connected to an angular flange 23 at its outer end, which flange is also connected to the tubular hub 10.

The rear end of the blade 22 preferably extends rearwardly to a distance somewhat beyond the rear end of the tubular hub, as clearly shown in Figure 4:. The pitch of the blades 22 is somewhat greater than the pitch of the blades 18, for purposes hereinafter made clear.

Assuming that my improved propeller was in actual use on an aeroplane, the air that is directly in front of the hub portion will be drawn by the blades through the hub 10, and said blades 20 will accelerate the travel of the air. In this connection, the reason for giving an increased pitch to the blades 18 over that of the propeller blades 13 is to create a suction that will draw a current of air into the hub from a path through the air slightly greater in diameter than the diameter of the interior of the tubular hub, and the reason for giving a still greater pitch to the propeller blades is because the air that strikes the propeller blades 22 is already moving at an increased rate of speed relative to the surrounding air, and by giving it this additionai pitch the movement of the air through the hub llll will be further accelerated by the rear propeller blades 22.

The advantage in having the rear edges of the propeller blades 22 project beyond the rear of the tubular hub is to carry the air that passes through the hub at an increased rate of speed to a point beyond the hub, so that it may expand laterally.

By thus causing an accelerated travel of the air that lies in the path of the hub, then the air which lies in the path of the propeller, blades 13 will be relatively still and will not be started by reason of the impact of the central portion of the hub to more in an outward direction before being engaged by the propeller blades 13, but on the contrary there will be a tendency for the airlthat is engaged by the blades 13 to move inwardly toward the center of the hub,

i which tendency acts counter to the tendency of the air that is engaged by the blades 1?) to move centrifugally outwardly olt of the ends of the blades, and this retarding action caused by the hollow hub and its propeller blades gives an increased eiticiency to the propeller blades 13, in that it delays the movement of the air slipping on" radially from the outer ends of the blades.

Furthermore, the mechanical structure of the propeller gives greater strength and relative light Weight.

I claim as my invention:

lfIn a propeller, the combination of a tubular hub, a shaft supporting means at the center of the hub and a set of propeller blades extending from the shaft supporting means to the interior of the hub, the leading edges said propeller blades extending in advance of the hub, propeller blades secured to the exterior of the hub, the path of their leading edges being in the rear of the path of the leading edges of the blades in the interior of the hub, for the purposes' stated.

2. In a propeller, the combination of a tubular hub, propeller blades secured to the exterior oil? the hub, a shaft supporting means at the center of the hub and a set ol? propeller blades extending from the shaft supporting means to the interior of the hub, the leading edges of said propeller blades extending in advance the hub-and propeller blades secured to the exterior of the hub, said exterior blades having a loss 'pitchthan the propeller blades in the interior oif the hub, for the purposes stated.

Des Moines, Iowa, April 7, 1928.

' ANTHONY ASSALA.

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